This invention relates generally to dirt and oil seals for gear train housings associated with axle-mounted electric traction motors of electrically propelled traction vehicles, and it relates more particularly to an improved arrangement for sealing the annular gaps between gearcase sidewall and both the hub of an axle gear and the thrust flange of an adjacent motor support axle bearing.
Propulsion of an electric or a diesel-electric locomotive is accomplished by means of a plurality of traction motors mounted on the trucks of the locomotive between the wheels that are affixed to opposite ends of the respective axles. As is shown, for example, in U.S. Pat. No. 2,954,263, such a motor typically is hung from the associated axle, with its magnet frame or stator being supported by the respective housings of a pair of axle bearings. The pinion end of the motor shaft is drivingly coupled to the associated axle-wheel set by suitable gearing housed in a rugged gearcase made of either metal or a suitable non-metallic material. Because of their proximity to the road bed of the railroad track, the gearcase and the axle bearings are exposed during operation of the locomotive to a hostile environment of dirt and other undesirable contaminants. Therefore it is customary in this art to provide various sealing means for impeding ingress of dirt and other foreign matter into the gearcase and bearing regions and for impeding egress of lubricants from these components.
On the wheel side of a gearcase, a dynamic seal is required in the annular gap between the outboard sidewall of the relatively stationary gearcase and the rotating wheel hub. On the motor side, a static seal is required in the annular gap between the other sidewall of the gearcase and the non-rotatable housing of the motor support axle bearing. In the latter case, however, the static seal does not prevent undesirable migration of lubricating oil from the axle bearing region into the gearcase.
The prior art gearcase that is disclosed in U.S. Pat. No. 3,727,483 includes two seal-retaining annular grooves in the sidewall flange that circumscribes the axle on the motor side of the gearcase. One of these grooves overlies the axle bearing and accommodates the required static sealing means. The second groove overlies the hub of the rotatable axle gear inside the gearcase and accommodates a dynamic sealing unit that impedes the egress of gear lubricant. Another annular groove is disposed between the first and second grooves, and a hole at its lowest point provides a drain for gear lubricant that may leak through the sealing unit in the second groove and for lubricating oil from the axle support bearing that escapes through the interface between the hub of the axle gear and the adjacent end of this bearing. The middle groove and drain hole are intended to obviate migration of axle bearing lubricating oil into the gearcase.